This invention relates to a radio receiver for frequency shift keyed signals on an R.F. carrier.
British Patent Specification No. 1517121 describes such a radio receiver, in particular the demodulation circuit, in which the signal processing is performed at a low frequency and therefore instead of adopting a superheterodyne principle, a direct conversion takes place Patent Specification Nos. 41679/78 and 30578/79 (Vance 5 and Vance 8) describe modifications of this arrangement.
In these previous circuits the output of the demodulator is a digital waveform and for some applications an analogue signal is necessary.